92 Fox-no Lighting Issue

[G00nies]

1992 fod 5.0l GT
So, instrument cluster lights stopped working except for Hi Beam and other warning lights (which I tested and still work), but no backlighting exists. all fuses are fine. Turn signal indicators are also operational.
Dimmer switch works, but only controls the dome light on/off at this time.
Tested the headlight switch and it ALSO works.

is there a component that I am overlooking? Illumination relay?
Its been a few months since Ive driven the car regularly, but they were operational (last I remember) a few months ago.

Help!

 

[Mustang5L5]

Year of car?

 

[G00nies]

Year of car?

Ha, sorry. 1992 GT5.0L manual

 

[Mustang5L5]

Ah. Sorry I don't have the specific wiring diagrams for that.

Sounds like you lost the power that feeds the cluster for illumination. have tou pulled the cluster to see if any part of the ribbon circuit tape on the backside has burned out? If I had wiring diagrams I could tell you which wire was the feed from the dimmer to the cluster

 

[stykthyn]

All fuses are fine or appear fine?

 

[G00nies]

All fuses are fine or appear fine?

Yes

 

[stykthyn]

Ah. Sorry I don't have the specific wiring diagrams for that.

Sounds like you lost the power that feeds the cluster for illumination. have tou pulled the cluster to see if any part of the ribbon circuit tape on the backside has burned out? If I had wiring diagrams I could tell you which wire was the feed from the dimmer to the cluster

It's the pink wire coming from the dimmer iirc

 

[G00nies]

Ah. Sorry I don't have the specific wiring diagrams for that.

Sounds like you lost the power that feeds the cluster for illumination. have tou pulled the cluster to see if any part of the ribbon circuit tape on the backside has burned out? If I had wiring diagrams I could tell you which wire was the feed from the dimmer to the cluster

I can MANUALLY power up either side of the cluster with my power probe...

 

[FoxMustangLvr]

You may need a new dimmer switch, I think it controls/flows the power to the cluster?

 

[G00nies]

You may need a new dimmer switch, I think it controls/flows the power to the cluster?

Yeah, that's what I'm thinking but it turns the map light on and off just fine?
That doest mean that it could still be a bad dimmer?

 

[stykthyn]

Before investing in a new one, take yours apart and clean it. The copper contacts can get corroded.

 

[G00nies]

Before investing in a new one, take yours apart and clean it. The copper contacts can get corroded.

JUST REMOVED AND CAREFULLY CLEANED THE RHEOSTAT AND CONTACTS. it certainly helped the quirky dome light on/off point, but still no iinstrument cluster backlighting.
Also removed the 5 or 6 194 bulbs marked "ILL" for backlighting and also swapped contacts with known working ones, still no backlights.
BRAKE HI BEAM BATT Check Eng Low Coolant AIRBAG all work just fine. and turn signals

 

[Mustang5L5]

Trace the contacts for the bulbs back to where they plug in. Using a DMM, test for voltage on the harness when you put the lights on.

If none there, then you shou;d test the dimmer next for voltage out to instrument ILL. I have these diagrams home

 

[G00nies]

Trace the contacts for the bulbs back to where they plug in. Using a DMM, test for voltage on the harness when you put the lights on.

If none there, then you shou;d test the dimmer next for voltage out to instrument ILL. I have these diagrams home

Thanks, that would be helpful, I've had trouble finding the proper wiring diagrams going FROM the dimmer TO the cluster. I did check for power and ground at the H/L switch and it checked out

 

[G00nies]

Anyone know which wire to probe FROM dimmer TO Cluster Illumination?

 

[G00nies]

Also just realized that I have NO HVAC control panel back lighting either!
If this helps

 

[Mustang5L5]

Sounds more and more like the dimmer is your problem.

Highly recommend picking up a 1993 Mustang EVTM off ebay. Every wiring diagram you'll ever need with colors and such for your car.

I'll take a look at my diagrams tonight, but it's for a 1988. May be different

 

[G00nies]

Problem SOLVED! I deserve a whole bunch of ribbing but didnt have a proper schematic for my car and missed the SECOND 5A fuse on the panel once I got a LEGIBLE wiring diagram from PRO DEMAND.
Went right to it and VIOLA!

I went full retard on this one, but thanks for the help. On the Bright side, I learned alot about electrical !

 

[stykthyn]

Problem SOLVED! I deserve a whole bunch of ribbing but didnt have a proper schematic for my car and missed the SECOND 5A fuse on the panel once I got a LEGIBLE wiring diagram from PRO DEMAND.
Went right to it and VIOLA!

I went full retard on this one, but thanks for the help. On the Bright side, I learned alot about electrical !

I replaced a dimmer and multi function switch because of that fuse. That's why I asked about fuses in my first post.

 

[Mustang5L5]

Assume you mean the one is slot 13?

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